Organic acid produced by lactic acid bacteria from bekasam as food biopreservatives

Abstract

Bekasam is one of the Indonesian fish fermented products that contain lactic acid bacteria (LAB). Previous research has obtained four LAB strains which are considered as bacteriocin producers, have antibacterial activity against pathogenic bacteria from food. In addition to a bacteriocins, LAB produce another compounds, such as organic acids. This study aimed to determine the produced organic acids and their antibacterial activity during LAB growth against of Lactobacillus monocytogenes, Staphylococcus typhimurium, Escherichia coli, Bacillus cereus and Staphylococcus aureus, to determine the organic acid contents using HPLC and to identify LAB isolates using molecular method based on 16S rDNA sequences. The four LAB strains (BP (3), BP (20), BI (3) and SK (5)) were grown in MRS broth medium, then incubated at 37 °C for 48 hours and every 4 hours incubation was tested of titratable acid total (TAT), pH, LAB growth and antibacterial activity. The result showed that the exponential phase of bacteria growth occurred at 16-20 hours incubation and at the end of the exponential phase produced the highest antibacterial activity in the four LAB strains. The highest growth, TAT and antibacterial activity produced by the SK (5) strain. The highest organic acids content were lactic acid in the SK(5) strain and acetic acid in the BI(3) strain. Identification result indicated that BI(3), BP(3), and BP(20) strains were Pediococcus pentosaceus IE 3 with similarity of 98%, 97%, and 98%, respectively. While SK(5) strain showed 93% similarity to Lactobacillus plantarum subsp. plantarum NC 8. The four LAB strains produced organic acids and had antibacterial activity, so they can be developed as food biopreservatives.